1. Field of the Invention
This invention relates generally to RF connectors, and more particularly to RF transitional connectors of the type which electrically match and connect a planar electric circuit to a coaxial system.
2. Description of the Prior Art
Planar electrical circuits are well known in the art, particularly in the field of microwave technology. Such circuits include flat strip type conductors which may be etched onto a dielectric substrate or suspended in air. These conductors are also disposed close to an RF ground in such a way to provide a particular RF impedance for the circuit.
In order to couple planar circuits to other portions of an operating microwave system, it is often necessary to provide RF transitional connectors capable of connecting a coaxial cable or component to a particular planar conductor in the circuit, without significant loss due to interfacing two different modes of electrical propagation, i.e., coaxial and planar. It is desirable, therefore, that the characteristic impedance of both the coaxial system and the planar conductor be matched to one another, and further that the particular connector used carry this impedance between the coaxial and the planar conductor operating modes.
Prior art transitional connectors comprise a metallic coaxial connector body assembly, the system end of which is formed to mate with a coaxial connector. The other end of the transitional connector body usually takes the form of a rectangular flange which may be placed in abutment against a side of the planar circuit. A single conducting pin member extends coaxially through the transitional connector body and has one end thereof formed to electrically connect the pin member to the center pin in a coaxial connector. The other end of the pin member extends outwardly from the flange end of the transitional connector body, and may take the form of a narrow flat tab. This tab can be soldered or otherwise electrically connected to an edge of a planar conductor which runs near the side of the planar circuit structure.
It is apparent that the conventional transitional connector assembly may not operate entirely satisfactorily, due to the fact that one end of the single pin member extending therethrough is affixed to the edge of the planar conductor, while the other end of the pin member is subjected to both rotational and axial stresses when first engaging the coaxial connector center pin. These stresses cause the tabbed end of the pin member to break loose and interrupt electrical continuity with the planar conductor edge.
Various measures have been undertaken to prevent the transitional connector pin member from relative axial or rotational movement within the connector body. Such measures have included fluting a portion of the pin member which is seated within a dielectric supporting bead. The bead, in turn, can be staked to the connector body to thereby prevent rotation of the pin member. Axial movement of the pin member is restrained by providing a discontinuous cross section along a portion of the pin member, and allowing the supporting bead to engage this discontinuity to prevent relative axial movement.